In general, a global positioning system (GPS) is a space-based global navigation satellite system that provides location and time information at practically all times and for practically anywhere on the Earth when and where there is an unobstructed line of sight to four or more GPS satellites. Generally, a GPS receiver calculates a position of the receiver by precisely timing the signals sent by the GPS satellites. Each satellite continually transmits messages that include such information as the time the message was transmitted, the precise orbital information for the satellite, and the general system health and rough orbits of all GPS satellites. The GPS receiver utilizes the messages it receives to determine a transit time of each message and computes the distance to each satellite. These distances along with the satellites' locations are used to compute the position of the receiver.
In many instances, services providing navigational assistance rely on a well-defined and up-to-date cartographic database. Such a database may contain information about the topology of a road network as well as other relevant attributes, such as number of road lanes, types of pavement, and types of traffic-controls. Typically, manual processing is used to create and maintain such databases. For instance, an individual may drive through a region of interest to identify changes of roads and modify/update the database accordingly. Further, an individual may extract information about roads from cartographic resources such as overhead imagery or locational signals.
In contrast, GPS signals are typically easier to collect and may be analyzed to detect the locations of various attributes along points of interest and to refine/extract the topological structure of a road network. Thus, a need exists to further utilize GPS signals for identifying relevant attributes of road networks and points of interest along various segments of a driving route.